基于HomePlug1.0的电力线载波通信传输系统的信道研究与部分硬件实现
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摘要
在过去应用广泛的电力线被认为有很大的潜力用于数据通信。事实上，在最近的几十年，电力线已经被用于低速数据通信，在Lon Works，CEBus，and X-10等电力线标准中都有提及和应用，特别是在一些特定系统中用于传输控制和管理信号。然而，电力线由于其自身的噪声严重和不可预测的特点，而很少作为高速数据通信信道。但是，近年来通信和调制技术的发展，特别是自适应数字信号处理和错误检测及纠正技术，使电力线通信技术出现新的MAC层和物理层协议，其性能可以和一些专用有线网络以及最近十年流行的无线局域网技术想媲美。
在2001年，一个由13个公司(包括Cisco，Motorola,Intel，Panasonic，and Texas Instruments)组成的组成的标准组织——HomePlug Powerline联盟，颁布了完整的HomePlug1.0规范，改规范使基于正交频分复用技术，主要针对10Mb／s室内电力线网络技术。显然，电力线载波通信技术现在已经被看作使3种主要的室内网络解决方案之一，与以太网，无线局域网(IEEE 802.11x)相互补充。本文主要的研究对象使基于OFDM的电力线载波通信传输系统的物理层，对电力线载波信道进行了着重的分析，给出响应的估计算法以及硬件实现模块。
第一章介绍了宽带接入网络的发展，着重介绍了基于正交频分复用(OFDM)的室内电力线载波通信网络技术，给出HomePlug1.0协议规范，重点在于物理层和MAC层技术规范。
第二章分析了电力线载波通信信道特性，重点在于针对相应的信道特性对信道进行建模并，给出电力线信道下的信道估计方法和仿真结果。
第三章对困扰OFDM传输系统的非线性失真现象进行了讨论，分析了3种主要的降低非线性失真的方法，对其性能和复杂度进行比较，证明了使用编码方法用于降低系统PAPR值最有效。
第四章在前几章的理论基础上，提出了适合于HomePlug1.0的电力线载波通信接收机的系统方案，同时介绍了基于MPC860T的OFDM基带传输系统平台的嵌入式实现，对整个平台的硬件和软件构成都有较为详细的介绍。
The use of ubiquitous electrical wiring as a potential medium for communication signals has been suggested over past generations. Indeed, for some decades now, power line wires have been ?used for low-speed data communication, culminating in such standards and products as LonWorks, CEBus, and X-10, as well as many proprietary systems for the transmission of control and management signals. However, the power line has largely been dismissed as being too noisy and unpredictable to be useful as a practical high-speed communication channel. On the other hand, recent advances in communication and modulation methodologice, as well as in adaptive digital signal processing and error detection and correction, have opened the way for the development of effective medium access control and physical layer protocols that support power line communications(PLC) networks operating at speeds comparable to those obtained from specially wired and more recent wireless local area network In mid-2001,an industrial standards organization called the HomePlug Powerline Alliance, originally founded by 13 companies including Cisco, Motorola, Intel, Panasonic, and Texas Instruments, announced the completion of the HomePlugl.O specification for a l.0Mb/s class in-home power line networking technology based on orthogonal frequency-division multiplexing(OFDM). Products based on this industry standard are enjoying much positive attention in the market press from industry and produce analysts based on performance and case of use. It was clear that HomePlug is now recognized as one of three attractive in-home net working solutions, together with Ethernet and Wi-Fi(IEEE 802.11lx). This thesis presents the studies of the physical layer of power line communications, which is an OFDM-based transmission system. It gives feasible algorithms, and primary implementation of some key modules is discussed as well.
Chapter 1 gives a brief survey of the development of Broadband Access networks, after the introduction the main technology of Access networks, we give out the new in-home power line networking technology based on orthogonal frequency-division multiplexing(OFDM), and studies the general content of HomePlugl.O protocol, focusing on the Physical Layer and Mac Layer Specifications of the protocol.
Chapter II analyze the channel character of the power line communication channel, constructs a system model taking consideration of power line channels and the channel estimation algorithm based on pilots are investigated.
Chapter III, analyze some algorithm to increase the robustness to system nonlinearities in OFDM, compares the advantage and disadvantage of the popular three techniques of PAPR decrease, and proved coded technique is the most effective method for OFDM system.
Chapter IV advances a proposed systematic scheme of power line receivers in accordance with HomePlugl.O on the basis of analysis in Chapter III, present the implementation of an OFDM baseband transmission platform based on MPC860T embedded system.
在2001年，一个由13个公司(包括Cisco，Motorola,Intel，Panasonic，and Texas Instruments)组成的组成的标准组织——HomePlug Powerline联盟，颁布了完整的HomePlug1.0规范，改规范使基于正交频分复用技术，主要针对10Mb／s室内电力线网络技术。显然，电力线载波通信技术现在已经被看作使3种主要的室内网络解决方案之一，与以太网，无线局域网(IEEE 802.11x)相互补充。本文主要的研究对象使基于OFDM的电力线载波通信传输系统的物理层，对电力线载波信道进行了着重的分析，给出响应的估计算法以及硬件实现模块。
第一章介绍了宽带接入网络的发展，着重介绍了基于正交频分复用(OFDM)的室内电力线载波通信网络技术，给出HomePlug1.0协议规范，重点在于物理层和MAC层技术规范。
第二章分析了电力线载波通信信道特性，重点在于针对相应的信道特性对信道进行建模并，给出电力线信道下的信道估计方法和仿真结果。
第三章对困扰OFDM传输系统的非线性失真现象进行了讨论，分析了3种主要的降低非线性失真的方法，对其性能和复杂度进行比较，证明了使用编码方法用于降低系统PAPR值最有效。
第四章在前几章的理论基础上，提出了适合于HomePlug1.0的电力线载波通信接收机的系统方案，同时介绍了基于MPC860T的OFDM基带传输系统平台的嵌入式实现，对整个平台的硬件和软件构成都有较为详细的介绍。
The use of ubiquitous electrical wiring as a potential medium for communication signals has been suggested over past generations. Indeed, for some decades now, power line wires have been ?used for low-speed data communication, culminating in such standards and products as LonWorks, CEBus, and X-10, as well as many proprietary systems for the transmission of control and management signals. However, the power line has largely been dismissed as being too noisy and unpredictable to be useful as a practical high-speed communication channel. On the other hand, recent advances in communication and modulation methodologice, as well as in adaptive digital signal processing and error detection and correction, have opened the way for the development of effective medium access control and physical layer protocols that support power line communications(PLC) networks operating at speeds comparable to those obtained from specially wired and more recent wireless local area network In mid-2001,an industrial standards organization called the HomePlug Powerline Alliance, originally founded by 13 companies including Cisco, Motorola, Intel, Panasonic, and Texas Instruments, announced the completion of the HomePlugl.O specification for a l.0Mb/s class in-home power line networking technology based on orthogonal frequency-division multiplexing(OFDM). Products based on this industry standard are enjoying much positive attention in the market press from industry and produce analysts based on performance and case of use. It was clear that HomePlug is now recognized as one of three attractive in-home net working solutions, together with Ethernet and Wi-Fi(IEEE 802.11lx). This thesis presents the studies of the physical layer of power line communications, which is an OFDM-based transmission system. It gives feasible algorithms, and primary implementation of some key modules is discussed as well.
Chapter 1 gives a brief survey of the development of Broadband Access networks, after the introduction the main technology of Access networks, we give out the new in-home power line networking technology based on orthogonal frequency-division multiplexing(OFDM), and studies the general content of HomePlugl.O protocol, focusing on the Physical Layer and Mac Layer Specifications of the protocol.
Chapter II analyze the channel character of the power line communication channel, constructs a system model taking consideration of power line channels and the channel estimation algorithm based on pilots are investigated.
Chapter III, analyze some algorithm to increase the robustness to system nonlinearities in OFDM, compares the advantage and disadvantage of the popular three techniques of PAPR decrease, and proved coded technique is the most effective method for OFDM system.
Chapter IV advances a proposed systematic scheme of power line receivers in accordance with HomePlugl.O on the basis of analysis in Chapter III, present the implementation of an OFDM baseband transmission platform based on MPC860T embedded system.
引文
【1】 陈维千主编，“电力线载波通道”，水利电力出版社，1983；
【2】 John G．Proakis 著，张力军，张宗橙，郑宝玉等译，“数字通信”，电子工业出版社，2001．4；
【3】 Kaveh Pahtavan，Prashant Krishnamurthy 著，刘剑，安晓波，李春生等译，“无线网络通信原理与应用”，清华大学出版社，2002．11；
【4】 韩永魁，袁长海，方坤，马元堔等编著，“宽带IP接入技术”，人民邮电出版社，2003，1；
【5】 W. Richard Stevens "TCP/IP Illustrated Volume 1: The Protocols";
【6】 EIA-600.10 Introduction to the CEBus Standard;
【7】 EIA-600.31-PL Physical Layer & Medium Specification;
【8】 EIA-600.33-Coax Cable Physical Layer & Medium Specification;
【9】 HomePlug Alliance. HomePlug 1.0 Specification. Jun 2001;
【10】 IEEE 802.11a, IEEE Standard for Wireless LAN Medium Access Control and Physical Layer Specifications, Nov. 1999;
【11】 M.K.Lee, R.E.Newman, H.A.Latchman, S.Katar and L.yonge, HomePlug1.0 Powerline Communication LANs-Protocol Description and Performance Results, International Journal Of Communication Systems, 2000;
【12】 MPC860T User's Manual;
【13】 VxWorks Programmer's Guide Edition 1;
【14】 VxWorks Reference Manual Edition 1;
【15】 Tornado BSP Developer's Kit for VxWorks User's Guide Edition 1;
【16】 熊桂喜，王小虎等译，“计算机网络”第三版，清华大学出版社，1998．7；
【17】 韦乐平，“接入网”，人民邮电出版社，1997．7；
【18】 American National Standard for Methods of Measurement of Radio-Noise Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9kHz to 40 Ghz;
【19】 Ron Gershon, David Propp, and Michael Propp, A Token Passing Network for Poweriine Communications, IEEE Transactions on Consumer Electronics, Vol. 37, No.2, May 1991;
【20】 S.H.Muller and J.B.Huber, OFDM with reduced peak-to-average power ratio by optimum combination of partial transmit sequences, Electronics Letters, 27th February 1997, Vol.33, No 5;
【21】 Yu Ju Lin, Haniph A.Latchman, and Richard E.Newman, A comparative Performance Study of Wireless and Power Line Networks. IEEE Communication Magazine, April 2003;
【22】 Yu Ju Lin, Haniph A.Latchman, and Miniyu Lee, A Power Line Communication Network Infrastructure for the Smart Home, IEEE Wireless Communications. Dec 2002;
【23】 Peer Hasselmeyer, An Infrastructure for the Management of Dynamic Service Networks, IEEE Communication Magazine, April 2003;
【24】 Jose Abad, Agustin Badenes, Jorge Blasco, Judit carreras, Victor Dominguez, Extending the power Line LAN Up to the Neighborhood Transformer, IEEE Communication Magazine, April 2003;
【25】 M.K.Lee, H.A.Latchrnan, R.E.Newman, S.Katar, L.Yonge, Field Performance Comparison of IEEE 802.11b and HomePlug1.0, Proceedings of the 27th Annual IEEE Conference on local Computer Networks;
【26】 Woo-Joo Hwang, Makoto Wada, Hideki Tode and Koso Murakami, HomeMAC: QoS-based MAC Protocol for the Home Network, Proceedings of the 27th Annual IEEE Conference on local Computer Networks;
【27】 Dave Marples, Stan Moyer, In-Home Networking, IEEE Communication Magazine, April 2003;
【28】 Francisco Javier Canete, Jose Antonio Cortes, Luis Diez, and Jose Tomas Entrambasaguas, Modeling and Evaluation of the Indoor Power Line Transmission Medium, IEEE Communication Magazine, April 2003;
【29】 John A.C.Bingham, Multicarrier Modulation for Data Transmission: An Idea Whose Time Has Come; IEEE Communication Magazine, May 1990;
【30】 M.Zimmermann, K.Dostert. An Analysis of the Broadband Noise Scenario in Power line Networks[C]. Proceedings of the 4th International Symposium on Powerline Communications and its Application, Limerick, Ireland, 2000:27-31
【31】 Smith.A.A. Power line noise survey[J]. IEEE Trans on Electromagnetic Compatibility, 1972, EMC-14(1):31-32;
【32】 M.Zimmermann, K.Dostert. Analysis and Modeling of Impulsive Noise in Broad-Band Polwerline Communications. IEEE Transactions On Electromagetic Compatibility, VOL 44, NO. 1, FEBRUARY 2002;
【33】 赵云峰，汪晓岩，徐立中，赵明宇，《低压电力线噪声分析与建模》，电力系统通信，2003-1；
【34】 张有兵，程时杰，何海波，熊兰，J．Nguimbis，《抵押电力线高频载波通信信道的建模研究》，电力系统自动化，Vol．26，No．23，Dec 10，2002；
【35】 Morgan H, Robert.W.D. Attenuation of communication signals on residential and commercial Intrabuilding power distribution circuits[J]. IEEE Transactions on Electromagnetic compatibility, 1986, (4):220-230;
【36】 M.Zimmermann, K.Dostert, A Multipath Model for the Powerline Channel, IEEE Transactions on Communications, VOL 50, NO 4, APRIL 2002;
【37】 Michael J.Riezenman, Networks for homes, IEEE SPECTRUM, December 1999;
【38】 Niovi Pavlidou, Aristotle University of Thessaloniki, Power Line Communications: State of the Art and Future Trends, IEEE Communication Magazine. April 2003;
【39】 Haniph A.Latchman, Lawrence W.Yonge. Local Area Networking, IEEE Communication Magazine, April 2003;
【40】 Masao Nakagawa, Honggang Zhang, Hideaki Sato, Ubiquitous Homelin-ks Based on IEEE 1394 and Ultra Wideband Solutions, IEEE Communication Magazine,
April 2003;
【41】 F.Daffara and O.Adami, "A new frequency detector for orthogonal multicarrier transmission techniques, "in Proc. IEEE VTC'95, July 1995, pp. 804-809.
【41】 程卫国，冯峰等编著，“MATLAB 5.3应用指南”，人民邮电出版社，1999。
【42】 蒙以正编著，“MATLAB 5.Ⅹ应用与技巧”，科学出版社，1999。
【43】 刘元安等编著，“宽带无限接入和无线局域网”，北京邮电大学出版社，2000。
【44】 老元威，硕士论文，2003；
【45】 R.W.Bauml, R.F.H.Fischer and J.B.Huber, Reducing the peak-to-average power ratio of multicarrier modulation by selected map, Electronice Letters, 24th Oct, 1996,Vol.32,No 22
【46】 S.H.Muller and J.B.Huber, "OFDM with reduced peak-to-average power ratio by optimum combination of partil transmit sequences," elec.Letts., Vol,33,No.5, Feb 1997,pp 368-369.
【47】 David A. Wiegandt and Carl R.Nassar, "Peak-to average power reduction in high-performance high-throughput OFDM via pseudo-orthogonal carrier-interferometry coding, submitter to PIMRC 2001 IEEE international Symposium on Personal, Indoor and Mobile Radio Communication
【48】 C.Tellambura, "Comment: Multicarrier transmission peak-to-average power reduction using simple block code," Electron. Lett., Vol. 34, No.17, pp. 1646-1647,Aug.20, 1998.
【49】 D.Wulich, "Reduction of peak to mean ratio of multicarrier modulation using cyclic coding," Electron.Lett., Vol.32, No.5.pp. 432-433, Feb.29,1996
【50】 A.E.Jones, etc., "Block coding scheme for reduction of peak to mean envelope power ratio of multi-carrier transmission schemes," Electron. Lett., Vol.30. No.25, pp. 2098-2099,Dec.8,1994.
【51】 F.Tufvesson and T.Maseng, "Pilot assisted channel estimation for OFDM in mobile cellular systems," in Proc.IEEE 47th Vehicular Technology conference, Phoenix, USA, May 1997, pp. 1639-1643.
【52】 O.Edfors, M.Sandell, J.-J.van de Beek, S.K.Wilson and P. O.Borjesson, "OFDM channel estimation by singular value decomposition," in Proc, IEEE 46th Vehicular Technology Conference, Atlanta, GA, USA, Apr. 1996,pp.923-927.
【53】 J.Rinne and M.Renfors, "Pilot spacing in orthogonal frequency division multiplexing systems on practical channels," IEEE Trans. Consumer Electronics. vol.42,No.4,Nov. 1996.
【54】 G.-S.Liu and C.-H.Wei, "A new variable fractional sample delay filter with nonlinear interpolation," IEEE Trans. Circuits and Systems-Ⅱ: Analog and Digital Signal Processing, vol.39, no.2, Feb. 1992.
【2】 John G．Proakis 著，张力军，张宗橙，郑宝玉等译，“数字通信”，电子工业出版社，2001．4；
【3】 Kaveh Pahtavan，Prashant Krishnamurthy 著，刘剑，安晓波，李春生等译，“无线网络通信原理与应用”，清华大学出版社，2002．11；
【4】 韩永魁，袁长海，方坤，马元堔等编著，“宽带IP接入技术”，人民邮电出版社，2003，1；
【5】 W. Richard Stevens "TCP/IP Illustrated Volume 1: The Protocols";
【6】 EIA-600.10 Introduction to the CEBus Standard;
【7】 EIA-600.31-PL Physical Layer & Medium Specification;
【8】 EIA-600.33-Coax Cable Physical Layer & Medium Specification;
【9】 HomePlug Alliance. HomePlug 1.0 Specification. Jun 2001;
【10】 IEEE 802.11a, IEEE Standard for Wireless LAN Medium Access Control and Physical Layer Specifications, Nov. 1999;
【11】 M.K.Lee, R.E.Newman, H.A.Latchman, S.Katar and L.yonge, HomePlug1.0 Powerline Communication LANs-Protocol Description and Performance Results, International Journal Of Communication Systems, 2000;
【12】 MPC860T User's Manual;
【13】 VxWorks Programmer's Guide Edition 1;
【14】 VxWorks Reference Manual Edition 1;
【15】 Tornado BSP Developer's Kit for VxWorks User's Guide Edition 1;
【16】 熊桂喜，王小虎等译，“计算机网络”第三版，清华大学出版社，1998．7；
【17】 韦乐平，“接入网”，人民邮电出版社，1997．7；
【18】 American National Standard for Methods of Measurement of Radio-Noise Emissions from Low-Voltage Electrical and Electronic Equipment in the Range of 9kHz to 40 Ghz;
【19】 Ron Gershon, David Propp, and Michael Propp, A Token Passing Network for Poweriine Communications, IEEE Transactions on Consumer Electronics, Vol. 37, No.2, May 1991;
【20】 S.H.Muller and J.B.Huber, OFDM with reduced peak-to-average power ratio by optimum combination of partial transmit sequences, Electronics Letters, 27th February 1997, Vol.33, No 5;
【21】 Yu Ju Lin, Haniph A.Latchman, and Richard E.Newman, A comparative Performance Study of Wireless and Power Line Networks. IEEE Communication Magazine, April 2003;
【22】 Yu Ju Lin, Haniph A.Latchman, and Miniyu Lee, A Power Line Communication Network Infrastructure for the Smart Home, IEEE Wireless Communications. Dec 2002;
【23】 Peer Hasselmeyer, An Infrastructure for the Management of Dynamic Service Networks, IEEE Communication Magazine, April 2003;
【24】 Jose Abad, Agustin Badenes, Jorge Blasco, Judit carreras, Victor Dominguez, Extending the power Line LAN Up to the Neighborhood Transformer, IEEE Communication Magazine, April 2003;
【25】 M.K.Lee, H.A.Latchrnan, R.E.Newman, S.Katar, L.Yonge, Field Performance Comparison of IEEE 802.11b and HomePlug1.0, Proceedings of the 27th Annual IEEE Conference on local Computer Networks;
【26】 Woo-Joo Hwang, Makoto Wada, Hideki Tode and Koso Murakami, HomeMAC: QoS-based MAC Protocol for the Home Network, Proceedings of the 27th Annual IEEE Conference on local Computer Networks;
【27】 Dave Marples, Stan Moyer, In-Home Networking, IEEE Communication Magazine, April 2003;
【28】 Francisco Javier Canete, Jose Antonio Cortes, Luis Diez, and Jose Tomas Entrambasaguas, Modeling and Evaluation of the Indoor Power Line Transmission Medium, IEEE Communication Magazine, April 2003;
【29】 John A.C.Bingham, Multicarrier Modulation for Data Transmission: An Idea Whose Time Has Come; IEEE Communication Magazine, May 1990;
【30】 M.Zimmermann, K.Dostert. An Analysis of the Broadband Noise Scenario in Power line Networks[C]. Proceedings of the 4th International Symposium on Powerline Communications and its Application, Limerick, Ireland, 2000:27-31
【31】 Smith.A.A. Power line noise survey[J]. IEEE Trans on Electromagnetic Compatibility, 1972, EMC-14(1):31-32;
【32】 M.Zimmermann, K.Dostert. Analysis and Modeling of Impulsive Noise in Broad-Band Polwerline Communications. IEEE Transactions On Electromagetic Compatibility, VOL 44, NO. 1, FEBRUARY 2002;
【33】 赵云峰，汪晓岩，徐立中，赵明宇，《低压电力线噪声分析与建模》，电力系统通信，2003-1；
【34】 张有兵，程时杰，何海波，熊兰，J．Nguimbis，《抵押电力线高频载波通信信道的建模研究》，电力系统自动化，Vol．26，No．23，Dec 10，2002；
【35】 Morgan H, Robert.W.D. Attenuation of communication signals on residential and commercial Intrabuilding power distribution circuits[J]. IEEE Transactions on Electromagnetic compatibility, 1986, (4):220-230;
【36】 M.Zimmermann, K.Dostert, A Multipath Model for the Powerline Channel, IEEE Transactions on Communications, VOL 50, NO 4, APRIL 2002;
【37】 Michael J.Riezenman, Networks for homes, IEEE SPECTRUM, December 1999;
【38】 Niovi Pavlidou, Aristotle University of Thessaloniki, Power Line Communications: State of the Art and Future Trends, IEEE Communication Magazine. April 2003;
【39】 Haniph A.Latchman, Lawrence W.Yonge. Local Area Networking, IEEE Communication Magazine, April 2003;
【40】 Masao Nakagawa, Honggang Zhang, Hideaki Sato, Ubiquitous Homelin-ks Based on IEEE 1394 and Ultra Wideband Solutions, IEEE Communication Magazine,
April 2003;
【41】 F.Daffara and O.Adami, "A new frequency detector for orthogonal multicarrier transmission techniques, "in Proc. IEEE VTC'95, July 1995, pp. 804-809.
【41】 程卫国，冯峰等编著，“MATLAB 5.3应用指南”，人民邮电出版社，1999。
【42】 蒙以正编著，“MATLAB 5.Ⅹ应用与技巧”，科学出版社，1999。
【43】 刘元安等编著，“宽带无限接入和无线局域网”，北京邮电大学出版社，2000。
【44】 老元威，硕士论文，2003；
【45】 R.W.Bauml, R.F.H.Fischer and J.B.Huber, Reducing the peak-to-average power ratio of multicarrier modulation by selected map, Electronice Letters, 24th Oct, 1996,Vol.32,No 22
【46】 S.H.Muller and J.B.Huber, "OFDM with reduced peak-to-average power ratio by optimum combination of partil transmit sequences," elec.Letts., Vol,33,No.5, Feb 1997,pp 368-369.
【47】 David A. Wiegandt and Carl R.Nassar, "Peak-to average power reduction in high-performance high-throughput OFDM via pseudo-orthogonal carrier-interferometry coding, submitter to PIMRC 2001 IEEE international Symposium on Personal, Indoor and Mobile Radio Communication
【48】 C.Tellambura, "Comment: Multicarrier transmission peak-to-average power reduction using simple block code," Electron. Lett., Vol. 34, No.17, pp. 1646-1647,Aug.20, 1998.
【49】 D.Wulich, "Reduction of peak to mean ratio of multicarrier modulation using cyclic coding," Electron.Lett., Vol.32, No.5.pp. 432-433, Feb.29,1996
【50】 A.E.Jones, etc., "Block coding scheme for reduction of peak to mean envelope power ratio of multi-carrier transmission schemes," Electron. Lett., Vol.30. No.25, pp. 2098-2099,Dec.8,1994.
【51】 F.Tufvesson and T.Maseng, "Pilot assisted channel estimation for OFDM in mobile cellular systems," in Proc.IEEE 47th Vehicular Technology conference, Phoenix, USA, May 1997, pp. 1639-1643.
【52】 O.Edfors, M.Sandell, J.-J.van de Beek, S.K.Wilson and P. O.Borjesson, "OFDM channel estimation by singular value decomposition," in Proc, IEEE 46th Vehicular Technology Conference, Atlanta, GA, USA, Apr. 1996,pp.923-927.
【53】 J.Rinne and M.Renfors, "Pilot spacing in orthogonal frequency division multiplexing systems on practical channels," IEEE Trans. Consumer Electronics. vol.42,No.4,Nov. 1996.
【54】 G.-S.Liu and C.-H.Wei, "A new variable fractional sample delay filter with nonlinear interpolation," IEEE Trans. Circuits and Systems-Ⅱ: Analog and Digital Signal Processing, vol.39, no.2, Feb. 1992.
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